US3840345A - Self agglomerating fluidized bed reacting apparatus - Google Patents

Abstract

An apparatus for reacting finely divided material in a fluidized bed supported by a circular grate in relative circular motion with regard to a cell enclosing an auxiliary bed which has a bottom in free communication with the main fluidized bed and which is in hydrostatic equilibrium with the latter, whereby slag settled on the grate is sorted and extracted.

Description

O United States Patent 11 1 1111 3,840,345

Andr et al. 1 Oct. 8, 1974 1 SELF AGGLOMERATING FLUIDIZED BED 1,872,883 8/1932 Byrne 201/31 REACTING APPARATUS 2,091,587 8/1937 Engler et a1. 110/36 WA 11 2.175.610 10/1939 L' d 48 63 X Inventors: Godel Albert Andr, Paris France 2,421,120 5/1947 0 355616 et a1. .1. 23/27/11 ux 3,460,818 8/1969 Greaves et a1. 266/21 [73 Ass'gnee' 2 3 2532233352??? 323:2 53? 3,605,656 9/1971 Stribling 110/36 x Switzerland [22] Filed: June 23, 1972 Primary Examiner-Joseph Scovronek NOI: Attorney, Agent, or Firm--Michael Striker [52] US. Cl. 23/284, 23/252 R, 23/277 R,

23/314, 48/851, 60/3912, 75/26, 110/28 J, [57] ABSTRACT 110/36, 201/31, 202/121 5 g g 3 An apparatus for reacting finely divided material in a 23/3lXq8/63 73 5 zozllzlf fluidized bed supported by a circular grate in relative 201 110713 1 39 circular motion with regard to a cell enclosing an aux 39 209/11 266/'21 f iliary bed which has a bottom in free communication 75/2l i 20 with the main fluidized bed and which is in hydrostatic equilibrium with the latter, whereby slag settled on the l 56] References Cited grate is sorted and extracted.

UNITEDSTATES PATENTS r M 1,469,399 10/1923 Treat 48/69 10 Claims, 6 Drawing Figures PATENTEDUCT 8l974 3.840.345

saw ur 3 2 I l l l/11111 5 1 gi llllfl PATENTEDUCT 8 I974 sum ear 3 SELF AGGLOMERATING FLUIDIZED BED REACTING APPARATUS This invention relates to a process and apparatus of reacting finely divided material in a fluidized bed at a temperature evolving self-agglomerating conditions.

It is known that, under such conditions, when products resulting from the reaction become fusible, they agglomerate selectively among themeselves and cluster but do not agglomerate with the solid granulated raw material Due to this fact, as soon as the resulting clusters have reached a certain size, they decant in form of slag down to the bottom of the fluidized bed. Thus it is necessary, to avoid the blocking of fluidization by clustering, to eliminate this slag as soon as it is formed.

An object of the present invention is to provide a process which will permit this separation, in a state of a quasipurity, of slag formed by reaction in the selfagglomerating fluidized bed.

A further object and advantage of the invention resides in the fact that the flue dust elutriated from the reactor can be totally reinjected in the fluidized bed as it is practically free from slag.

Other objects of the present invention will become apparent in the course of the following specification.

According to the present invention, the solid granulated raw material treated in a self-agglomerating fluidized bed is contained in a reactor the cylindrical base of which includes a circular fluidization grate blown by reacting fluidizing gas, which grate constitutes a support for said solid granulated raw material. Above this grate is located a so-called fluidization sorting cell which is set for separation and extraction of the slag (in state of quasi-purity). Actually, this extraction takes place at the shallow end of an auxiliary fluidized bed of small depth, contained in the cell, which auxiliary fluidized bed is in communicaton and in hydrostatic equilibrium with the main fluidized bed.

In accomplishment of the objectives of the present invention, the cell is in relative circular motion with regard to the grate. The cell has a bottom lateral opening for the aforementioned communication causing an hydrostatic equilibrium between the two fluidized beds, and allowing the penetration of the slag into the cell.

Additional gas is blow into the fluidization sorting cell over the auxiliary fluidized bed, by which slag settled at the shallow end of said auxiliary fluidized bed is uncovered, sorted and extracted in quasi pure state.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing, by way of example only, several constructions of a reactor according to the invention as well as the fluidization cell constituting its essential part.

In the drawings:

FIGS. 1 to 4 are side views, partly broken off, of different fluidization reactors.

FIG. is a perspective view on a larger scale of a fluidization sorting cell designed in view of an outward ex traction of the slag.

FIG. 6 is a similar perspective view of a fluidization sorting cell designed in view of an inward extraction of the slag.

FIG. 1 shows a cylindrical reactor 1 of the present invention containing a circular horizontal grate 2. Above the grate is a fluidization sorting cell 3 having a lateral bottom opening 0 and a front opening 4 for the extrac- 2 tion of slag toward an ash pit (not shown) located outside of the reactor. The reactiongas is introduced through the pipe 5 while gas emerging from the reaction is evacuated through the pipe 6 after having eventually passed through a cyclone 7 used to assure the collection and reinjection of flue dust into the fluidized bed. Solid granulated raw material is supplied to the re-' actor through the pipe 8. g

In the above-mentioned representation of the invention, the relative motion between grate and cell results from the motion of the grate which rotates round its axis x-y, the cell being fixed.

FIG. 2 shows a partly conical and partly cylindrical reactor 1' of the present invention which has a circular inclined grate 2. Above the grate is a fluidization sorting cell 3 having a lateral bottom opening 0' and a from opening 4' for the extraction of slag towards an ash pit (not shown), located outside of the reactor. Additional reaction gases at a high temperature are introduced by several lateral nozzles one of which is shown at 10. The reaction gas is introduced through the pipe 5' while gas emerging from the reaction is evacuated through the pipe 6' after having eventually passed through a cyclone 7 used to assure the collection and reinjection of flue dust into the fluidized bed. The reactor is supplied with solid granulated raw material through a pipe 8' located at the level of the cyclone so as to assure the reinjection into the reactor of a mixture with the flue dust.

In the above-mentioned representation of the invention, the relative motion between grate and cell results from the motion of the grate whitih rotates round its axis x y, the cell being fixed and located at the highest level above the grate.

FIG. 3 shows a cylindricalfluidization reactor 1'' of the present invention containing a horizontal circular annular grate 2". Above it is a fluidization sorting cell 3', having a lateral bottom opening 0' and a rear opening 4" for the extraction of the slag toward the interior of the reactor. This horizontal annular grate is located between the outer cylindrical wall of the reactor 1" and an interior cylinder 9" constituting an ash pit which is intended to receiveslag' discarded at 4". The reaction gas is introduced through the pipe 5" and the gas emerging from the reaction is evacuated through the pipe6 after havingeve'ntually passed throug'h a cyclone 7 used to assure the collection and reinjec tion of flue dust into the fluidized bed. The supply of solid granulated raw material takes place through the pipe 8". v

In the afore-mentioned representation of the invention, two alternatives are possible to obtain the relative motion between grateand cell: the grate may rotate round its vertical axis x y", the cell being fixed, or reversely, the grate may be fixed and the cell may rotate round the axis x" y".

FIG. 4 shows a cylindrico co'nical reactor 1" of the present invention containing a circular, annular inclined grate 2". Above it is a fluidization sorting cell 3 having a lateral bottom opening 0"" and a rear opening 4" for the extraction of sla'g toward an ash pit 9" located within the reactor. Additional reaction gases at high temperature are introduced through several nozzles one of Which is shown at lfl' 'h The inclined annular grate 2" is located between the outer cylindrical wall of the reactor-1" and an inner cylinder 9" intended to receive slag discarded out at 4". The

reaction gas is introduced through the pipe 5" and th gas emerging from the reaction is evacuated through the pipe 8" after having eventually passed through the cyclone 7" used to assure the collection and reinjection of flue dust into the fluidized bed mixed with solid granulated raw material subjected to reaction which has been introduced through the pipe 8' at the level of the cyclone.

In the afore-mentioned representation of the invention, twoalternatives are also possible to obtain the relative motion between grate and cell, that is to say the grate may rotate round its inclined axis x' y', the cell being fixed and located at the highest level above the grate, or reversely the grate may be fixed and the cell may rotate round the inclined axis x' y.

FIG. 5 shows on an enlarged scale a fluidizing sorting cell made to divert the slag toward an ash pit situated outside of the reactor, as shown in FIGS. 1 and, 2. This cell is placed directly above the grate 2 which is in the illustrated embodiment supposed to rotate in the direction of the arrow, namely,counterclockwise. The cell includes lateral vertical walls a, b, c and d upon which is mounted a top wall constituting a top of a box-like structure which is tight. V

Within the cell, the grate supports a fluidized bed, described as an auxiliary fluidizedbed, which communicates by opening 0, at the base of the wall a (the wall a does not extend down to the grate) with the main fluidized bed located in the cylindrical reactor and extending above the cell.

The wall a is arranged to provide free introduction of slag entrained by the rotary movement of the grate. For that purpose, it is open at its base to a height which will avoid any danger of blocking by the slag. This might require an opening having a height of 1 foot or more.

The vertical lateral walls are shaped to adapt them to their particular functions.

Thus the function of the wall a is to provide by its opening 0 a communication-between the auxiliary fluidized bed and the main fluidized bed. For that purpose, the wall a is largely open at its base.

As far as the wall I; is concerned (which coincides with the cylindrical wall of the reactor), its function is to assure the discharge of the slag through the opening 4 and provide access to the ash pit located outside of the reactor.

The function of the wall c is to guide the slag moved by the rotation of the grate toward the opening 4.

Actually the wall 0 can be rectilinear and oblique relatively to the arrival of the slag but the best result for their sweeping and rejection is produced by curving the vertical wall c following the trace of a logarithmical spiral the convex side of which is directed toward the interior of the cell; this curve is particularly advantageous since it has at all pointsan angle which is Constant relatively to the direction of incidence of slag moved by the grate.

Another function of the wall 0 is to avoid that the main fluidized bed enters into the cell by this side.

FIG. 6 shows on an enlarged scale a cell made to divert the slag' toward an ash pit situated at the center of the reactor, the circular grate being in this case of an annular shape, as shown in FIGS. 3 and 4. This cell is placed directly above the grate 2'.

For this representation, two alternatives may be used: the grate may rotate in the direction of the arrow, namely counterclockwise, the cell being fixed, or the grate may be fixed and the cell will rotate in the direction opposite to that shown of the arrow, that is to say clockwise, so that the slag decanted over the grate is forced into the cell.

The cell includes lateral vertical walls ab'c' and d,

. upon which is mounted a top wall constituting a top of a box-like structure which is tight. Within the cell, the grate supports a fluidized bed described as an auxiliary fluidized bed which communicates by opening 0' at the base of wall a (the wall a does not extend down to the grate) with the main fluidized bed'located in the cylindrical reactor and extending above the cell. The wall a is arranged to provide free introduction of slag entrained by the relative rotary movement existing between grate and cell. For that purpose, it is opened at its base to a height which will'avoid any danger of blocking by the slag. This might require an opening having a height of '1 foot or more.

The vertical lateral walls are shaped to adapt them to their particular function.

Thus the function of the wall a is to provide by its opening 0' a communication between the auxiliary fluidized bed and the main fluidized bed. For that purpose, the wall a is largely opened at its base.

The function of walls b and c is to avoid that the main fluidized bed enters the cell on their respective sides, but the major function of wallc' is to guide the slag toward the central opening 4'. Actually the wall c can be rectilinear and oblique relatively to the direction of the arrival of the slag but the best result for their sweeping and rejection is obtained'by curving the vertical wall 0' following the trace of a logarithmic spiral the concave side of which is directed toward the interior of the cell; as'mentioned above, this curve is particularly advantageous since it has at all points a constant angle relatively to the direction of incidence of slag.

The operation of the two above-described types of fluidization sorting cells is as follows:

Fluidization gases which emerge from the auxiliary fluidization bed located within the cell, cannot find any other exit except the open space 0 at the bottom of the wall a. They create in the cell a counter pressure which balances'hydros'tatically the auxiliary fluidized bed'with the main fluidized'bed.

The result is that the surface of the auxiliary bed is I automatically limited to the height of the base of the wall a. Actually this is precisely the case in the vicinity of. this wall, but since a large quantity of particles of the auxiliary fluidized bed is entrained'by the gases'toward the opening and then toward the main fluidized'bed, the result is that the depth of the auxiliary fluidized bed will diminish fairly rapidly at a'short distance from the wall a, so that the slag settled upon the grate becomes uncovered. Actually this slag canthen be evacuated toward the ash pit in a quasi-pure condition.

For all the examples above represented, further gas can be blown into the fluidization sorting cell over the auxiliary fluidized bed. Such gas may not be only reaction gases but eventually can be other gases and/or steam. I

Due to the fact that the main fluidized bed and the auxiliary fluidized bed operate bothparallely, and furvention, the reactor is'used for gasification of coal, the treating power obtained will correspond to 2,000 Kg per square meter of-circular grate. expressed in coal treated at atmospheric pressure, the treating power being, of course, considerably increased if gasification As far as the operation of the reactor constituting the subject of the present invention is concerned, it depends to a great extent on the use for which it is intended, such as the uses described hereinafter.

in any event, a light-up fuel oil burner or gas burner is used to provide the necessary temperature to the solid granulated material lying in static manner upon the grate. It is only after heating and ignition of the static layer that it should be blown to fluidize it, then continuous feed of the solid granulated raw material takes place usually by injections into the fluidized bed at a point represented in the drawings by the numerals 8, 8', 8", 8", depending on the construction.

When using the described reactors for carrying out certain highly endothermic reactions (such as gasification by steam), or reactions requiring a very high temperature, such as the making of cement, it is advantageous to use one or the other of the following improvements which can be used singly or in combination:

a. Additional reaction gases may be injected at a very high temperature (which may reach 1,000C) by known means through one or several nozzles 10' or 10" placed above the fluidizing grate of FIGS. 2 or 4, into the fluidized bed. Then the fluidized bed becomes a so-called expanded fluidized bed which obviously will require an increased separation capacity of the cyclone above the reactor.

b. The initial solid granulated raw material is not injected any more into the base of the reactor but into the cyclone located above it, as represented FIGS. 2 and 4, which makes it possible to reheat it starting with calories contained in the gases emerging from the reactor and thus to introduce the raw material at a high temperature in a mixture with the flue dust into the reactor. It is also possible to provide an operation which is even more methodical and which permits to recover practically in totality the calories entrained by the gases emerging from the reactor. To achieve this it is sufficient to provide above the reactor a group of several cyclones (not represented) through which flue gases pass in series and to move in counter current in opposite direction the solid granulated raw material which is introduced into the reactor, as well as the flue dust picked by the cyclones.

c. One or a plurality of conventional fluidizing grates are added in superposition above the surface of the afore-mentioned gasifying fluidized bed, in view of submitting the effluent producer gas:

either to a counter-current flow of gas with the aforementioned solid granulated raw material,

or to successive treatments in fluidized conditions with various products adapted to carry out useful chemical reactions such as desulphurization. methanisation, etc.

Among the uses and the advantages of the process of the present invention, the following can be enumerated;

The process of the present invention makes it possible to carry out diverse reactions in a selfagglomerating fluidized bed under normal or pressurized conditions. These reactions include namely: pelletizing carbonization of bituminous coal, gasification of combustibles under normal or pressurized conditions, such gas to be burned either directly under power plant boilers or desulphurized prior to its use for high efficiency power production in combined cycle or for processing in various manner.

Other possible applications concern the production of cement, the reduction of ore, etc.

What is claimed is:

1. An apparatus for reacting finely divided materials in a fluidized bed at a temperature involving selfagglomerating conditions under which slag sinks gradually through said fluidized bed, comprising an at least partly cylindrical reactor; a circular grate element located within said reactor and adapted to carry a main fluidized bed and slag which settles through the same onto said grate member; a cell element overlying a portion of said grateelement and defining with the same an enclosed space which is open at the bottom to said grate element and adapted to accommodate an auxiliary shallow fluidized bed, said cell 'element having a side wall oriented substantially radially and formed with an inlet opening communicating said fluidized beds with one another and through which slag enters said space, and a substantially circumferential end wall formed with an outlet opening for the slag; means for imparting to one of said elements a circular motion relative to the other of said elements, so that fluidized-bedmaterial and slag settled on said grate element enter said space through said inlet opening; and means for blowing a reacting fluidizing gas through said grate element into said fluidized beds for maintainingthem in hydrostatic equilibrium with one another and for sorting and extracting slag in said cell element from said auxiliary shallow fluidized bed through said outlet opening.

2. An apparatus as defined in claim 1, wherein said grate element rotates in a horizontal plane; and wherein said cell element is stationary and said endwall formed with said outlet opening faces radially outwardly of said reactor.

3. An apparatus as defined in claim 1, wherein said grate element rotates in an inclined'plane; and wherein said cell element is stationary and said outlet opening is located at the highest level of said grate element and faces outwardly of said reactor.

4. An apparatus as defined in claim 1; further comprising means defining a discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and rotating in a horizontal plane; and wherein said cell element is stationary and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same. 7

5. An apparatus as defined in claim 1; further comprising means defininga discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and rotating in an inclined plane; and wherein said cell element is stationary and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same.

6. An apparatus as defined in claim 1; further comprising means defining a discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and being stationarily located in a horizontal plane; and wherein said cell element rotates with reference to said grate element and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same.

7. An apparatus as defined in claim 1, wherein said cell element has another side wall spaced from and opposite the first-mentioned side wall, said other side wall being contoured to the shape of alogarithmic sprial.

8. An apparatus as defined in claim 1; further comprising a plurality of nozzles communicating with the interior of said reactor upwardly of said grate element; and means for introducing through said nozzles and into said main fluidized bed reaction gases having a higher temperature than said reacting fluidizing gas which is blown through said grate element.

9. An apparatus as defined in claim 1; and further comprising at least one cyclone located above said reactor and communicating therewith for receiving preheated solid granulated primary material through calorific exchange in countercurrent with gases in'said cyclone.

10. An apparatus as defined in claim 1; and comprising means for blowing further gas into said cell element.

Claims (10)

1. AN APPARATUS FOR REACTING FINELY DIVIDED MATERIALS IN A FLUIDIZED BED AT A TEMPERATURE UNVOLVING SELF-AGGLOMERATING CONDITIONS UNDER WHICH SLAG SINKES GRADUALLY THROUGH SAID FLUIDIZED BED, COMPRISING AN AT LEAST PARTLY CYLINDRICAL REACTOR; A CIRCULAR GATE ELEMENT LOCATED WITHIN SAID REACTOR AND ADAPTED TO CARRY A MAIN FLUIDIZEED BED AND SLAG WHICH SETTLES THROUGH THE SAME ONTO SAID GATE MEMBER, A CELL ELEMENT OVERLYING PORTION OF SAID GATE ELEMENT AND DEFINING WITH THE SAME AN ENCLOSED SPACE WHICH IS OPEN AT THE BOTTOM TO SAID GRATE ELEMENT AND ADAPTED TO ACCOMMODATE AN AUXILIARY SHALLOW FLUIDIZED BED, SAID CELL ELEMENT HAVING A SIDE WALL ORRIENTED SUBSTANTIALLY RADIALLY AND FORMED WITH AN INLET OPENING COMMUNICATING SAID FLUIDIZED BEDS WITH ONE ANOTHER AND THROUGH WHICH SLAG ENTERS SAID SPACE, AND A SUBSTANTIALLY CIRCUMFERENTIAL WND WALL FORMED AN OUTLET OPENING FOR THE SLAG; MEANS FOR IMPARTING TO ONE OF SAID ELEMENTS A CIRCULAR MOTION RELATIVE FOR IMPARTING TO ONE OF SAID ELEMENTS A CIRCULAR MOTION RELATIVE AND SLAG SETTLED ON SAID GRATE ELEMENT ENTER SAID SPACE THROUGH SAID INLET OPENING; AND MEANS FOR BLOWING A REACTING FLUODIZING

2. An apparatus as defined in claim 1, wherein said grate element rotates in a horizontal plane; and wherein said cell element is stationary and said end wall formed with said outlet opening faces radially outwardly of said reactor.

3. An apparatus as defined in claim 1, wherein said grate element rotates in an inclined plane; and wherein said cell element is stationary and said outlet opening is located at the highest level of said grate element and faces outwardly of said reactor.

4. An apparatus as defined in claim 1; further comprising means defining a discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and rotating in a horizontal plane; and wherein said cell element is stationary and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same.

5. An apparatus as defined in claim 1; further comprising means defining a discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and rotating in an inclined plane; and wherein said cell element is stationary and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same.

6. An apparatus as defined in claim 1; further comprising means defining a discharge passage at the center of said reactor; said grate element being annular, surrounding said discharge passage and being stationarily located in a horizontal plane; and wherein said cell element rotates with reference to said grate element and said outlet opening faces inwardly of said reactor and communicates with said discharge passage for discharging slag into the same.

7. An apparatus as defined in claim 1, wherein said cell element has another side wall spaced from and opposite the first-mentioned side wall, said other side wall being contoured to the shape of a logarithmic sprial.

8. An apparatus as defined in claim 1; further comprising a plurality of nozzles communicating with the interior of said reactor upwardly of said grate element; and means for introducing through said nozzles and into said main fluidized bed reaction gases having a higher temperature than said reacting fluidizing gas which is blown through said grate element.

9. An apparatus as defined in claim 1; and further comprising at least one cyclone located above said reactor and communicating therewith for Receiving preheated solid granulated primary material through calorific exchange in countercurrent with gases in said cyclone.

10. An apparatus as defined in claim 1; and comprising means for blowing further gas into said cell element.

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